1. Field of the Invention
This invention relates to a carrier for sensitive devices and method for removing the sensitive devices constructed in a sub-assembly from a main assembly. In particular, this invention relates to a carrier and a removal assembly, such as a wafer stage carrier and removal assembly, to remove the wafer stage carried by the wafer stage carrier from an exposure apparatus. The exposure apparatus may be the type used in a photolithography process to manufacture semiconductor substrates.
2. Description of the Related Art
In manufacturing integrated circuits using a photolithography process, light is transmitted through non-opaque portions of a pattern on a reticle, or photomask, through a projection exposure apparatus, and onto a wafer of specially-coated silicon or other semiconductor material. The uncovered portions of the coating, that are exposed to light, are cured. The uncured portions of the coating are removed by an acid bath. Then, the layer of uncovered silicon is altered to produce one layer of the multi-layered integrated circuit. Conventional systems use visible and ultraviolet light for this process. Recently, however, visible and ultraviolet light have been replaced with electron, x-ray, and laser beams, which permit smaller and more intricate patterns.
As the miniaturization of a circuit pattern progresses, the focus depth of the projection exposure apparatus becomes very small, making it difficult to align accurately the overlay of circuit patterns of the multi-layered integrated circuit. As a result, a primary consideration for an overall design of the photolithography system includes building components of the system that achieve precision by maintaining small tolerances. Any vibration, distortion, or misalignment caused by internal, external or environmental disturbances must be kept at minimum. When these disturbances affect an individual part, the focusing properties of the photolithography system are collectively altered.
Occasionally, a portion of the photolithography system, i.e., a carrier of a sub-assembly, needs to be removed from the main assembly for servicing purposes, periodic maintenance, or other reasons. In one example, the sub-assembly may be a wafer stage carried by a wafer stage carrier that needs to be removed from the exposure apparatus as the main assembly. In an extremely sensitive and delicate system, such as the photolithography system where any types of disturbances, such as vibration, heat, and the like, may alter the accurate alignment of the system, there is a need for a wafer stage carrier and method to remove the wafer stage carrier from the exposure apparatus without causing any disturbances, or with minimized disturbances, to other parts and components of the photolithography system.
The advantages and purposes of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purposes of the invention will be realized and attained by the elements and combinations particularly pointed out in the appended claims.
To attain the advantages and consistent with the principles of the invention, as embodied and broadly described herein, a first aspect of the invention is a carrier for sensitive devices to facilitate removing the sensitive devices constructed in a sub-assembly from a main assembly. The sub-assembly is removably attached to the main assembly. The carrier comprises a set of expandable supports, when in an expanded state, supporting the sub-assembly on a stationary surface, and a set of removal supports to support and remove the sub-assembly away from the main assembly after detaching the sub-assembly from the main assembly.
A second aspect of the present invention is a method for removing a carrier for sensitive devices constructed in a sub-assembly from a main assembly. The method comprises expanding a set of expandable supports until the sub-assembly is supported thereby on a stationary surface, and detaching the sub-assembly from the main assembly. The method also comprises reducing expansion of the set of expandable supports to remove the sub-assembly from the main assembly.
A third aspect of the present invention is a wafer stage carrier for carrying a wafer stage assembly. The wafer stage carrier is removably connected to an apparatus frame of an exposure apparatus. The wafer stage carrier comprises a wafer stage base plate having a plurality of body supports for attaching the wafer stage carrier to the apparatus frame, and a set of expandable supports, which when in an expanded state, supports the wafer stage carrier on a stationary surface. The wafer stage carrier also comprises a set of removal supports to support and remove the wafer stage carrier away from the exposure apparatus after detaching the wafer stage carrier from the apparatus frame of the exposure apparatus.
A fourth aspect of the present invention is a method for removing a wafer stage carrier from an exposure apparatus. The wafer stage carrier is removably connected to an apparatus frame of the exposure apparatus. The method comprises expanding a set of expandable supports until the wafer stage carrier is supported thereby on a stationary surface, and detaching the wafer stage carrier from the apparatus frame. The method also comprises reducing expansion of the set of expandable supports to remove the wafer stage carrier from the exposure apparatus.
A fifth aspect of the present invention is a method for attaching a carrier for devices constructed in a sub-assembly to a main assembly. The method comprises expanding at least one expandable support until the sub-assembly is supported thereby on a stationary surface, attaching the sub-assembly to the main assembly, and reducing expansion of the at least one expandable support to support the sub-assembly by the main assembly.
A sixth aspect of the present invention is a method for making an exposure apparatus comprising steps of providing a main assembly including an exposure device, and removably attaching a sub-assembly to a part of the main assembly with a removal device. The removal device comprises at least one expandable support, when in an expanded state, supporting the sub-assembly on a stationary surface, and at least one removal support to support and remove the sub-assembly away from the main assembly after detaching the sub-assembly from the main assembly.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. Additional advantages will be set forth in the description which follows, and in part will be understood from the description, or may be learned by practice of the invention. The advantages and purposes may be obtained by means of the combinations set forth in the attached claims.